Drafting apparatus



Jan. 22, 1963 c. H. LITTLE 3,074,173

DRAFTING APPARATUS 3 Sheets-Sheet 1 Filed Feb. 9, 1959 I INVENTOR. l 6/01424517065420 [1777.5

1: f i 6 v A 92 %,W

\Ii /76 6 ATTOPNE Y5 BYM Jan. 22, 1963 c. H. LITTLE DRAFTING APPARATUS 3Sheets-Sheet 2 Filed Feb. 9. 1959 Eli;

INVENTOR. Cannes/ vamp l/rrze Arne/vars F II Jan. 22, 1963 c. H. LITTLEI DRAFTING APPARATUS Filed Feb. 9. 1959 3 Sheets-Sheet 3 3,074,173DRAFHNG APPARATUS Charles Hubbard Little, Pepper Pike, @hio, assignor toUniversal Drafting Machine Corporation, Cleveland, llhio, a corporationof Ohio Filed Feb. 9, 1959, ger. No. 792,tl75 It) Claims. (Cl. 3376) Thepresent invention relates to so-called drafting machines and moreparticularly to drafting machines having one or more straight edges,rulers, triangles, etc., connected to a member movable upon a lineartrack.

In the machines of the character referred to, the ruler or rulers, etc.,are usually pivotally connected to the member, which member is in turnmovable upon the linear track and the member which provides the track isin turn movable upon a second linear track positioned at right angles tothe first.

One of the principal objects of the invention is the provision of a newand novel drafting machine or like apparatus of the character referredto which will be simple, stable and rugged in construction and thereforeaccurate in operation, economical to manufacture and maintain, and lowin friction, light in weight and therefore extremely easy to operate.

Another object of the invention is the provision of a new and noveldrafting machine or like device of the character mentioned, which can bereadily manufactured for use with boards of any practical size and inwhich machine there will be a minimum of deflection and sag although therail members are supported at only two points.

Another object of the invention is the provision of a new and noveldrafting machine or like device comprising an X or Y beam or rail havinga relatively narrow centrally located track along which the carriagemoves and wherein the track proper is enclosed and thus protectedagainst dirt, damage, etc.

Another object of the invention is the provision of a new and noveldrafting or like device of the character referred to having acounterweight movably supported in the Y beam or rail and connected tothe carriage movable along the rail or track to provide proper balanceat all board angles automatically and which does not overhang the boardand is completely out of the way at all times.

The invention resides in certain novel constructions and arrangements ofparts, and further objects and advantages will appear from the followingdescription of the preferred embodiment described with reference to theaccompanyin drawings, which form a part of this specification, and inwhich like reference characters designate corresponding parts throughoutthe several views, and wherein:

FIG. 1 is a fragmentary plan view of a drafting table or board having adrafting machine embodying the present invention attached thereto;

FIG. 2 is an enlarged fragmentary plan view with portions broken awayand in section of the drafting machine shown in H6. 1;

H6. 3 is a sectional view with portions in elevation approximately onthe line 33 of FIG. 2;

FIG. 4 is an enlarged sectional view with portions in elevationapproximately on the line 4-t of FIG. 3;

PEG. 5 is an enlarged sectional view with portions in elevationapproximately on the line 55 of FIG. 2;

E16. 5 is an enlarged sectional view with portions in elevationapproximately on the line 66 of FIG. 2; and

FIG. 7 is a fragmentary sectional view approximately on the line 7'7 ofFIG. 2.

Although the preferred embodiment of the invention is herein shown anddescribed in detail, it is to be underbtates Fatent hh'l l lld stoodthat the invention is not limited to the constructions and arrangementsof the parts shown and described, but is capable of being otherwiseembodied and of being practiced and carried out in various ways.

Referring to the drawings, the apparatus shown therein comprises a pairof rulers A, 3 extending at right angles to one another and movable overthe working surface of a drafting table or board C. The rulers, commonlycalled drafting machine scales, are detachably connected to a rulersupporting member D pivotally connected to a protractor assembly orprotractor E for movement or adjustment about an axis normal to thesurface of the board C. The protracto-r E comprises a flexibleattachment plate or blade which is in turn detachably connected to a Ycarriage F movable upon a linear Y beam or rail C- extending downwardlyfrom the upper edge of the board C, as viewed in the drawings at rightangles thereto.

The vertical beam G is pivotally connected, for oscillation about anaxis generally parallel with the upper edge of the board C, to a secondor X carriage H movable upon a linear X earn or rail J extendinggenerally parallel with the upper edge of the board C and at rightangles to the length of the vertical beam G. The beams G, J are prefrably made of extruded aluminum alloy and in such a shape that they areextremely resistant to deflection or distortion, etc. in all directions.The horizontal rail beam I is connected to the board C at only twospaced points so that warpage and other distortion of the board C willnot be imparted to the beam. With this construction the normal come andgoinherent in drafting boards and tables will not be reflected in thehorizontal beam .l.

The beams G, J are identical in construction and each comprises a lengthof beam the cross-sectional shape of which is clearly shown in FIG. 3and which resembles somewhat the shape of a conventional l-beam, in thatit has a central web l5 and pairs of flanges 17, 1% and 20, 21 adjacentto opposite longitudinal edges of the web projecting to opposite sidesthereof. The beam is symmetrical about its longitudinal, central plannormal to its web, with the result that the flanges on either side ofthe web are alike. In addition to the edge flanges 17, 13 and Eli, 211each beam has a further longitudinal flange Z2 projecting from the topside of the web 15 as viewed in PEG. 3 and located midway between theflanges 17, 26 that is, the edge flanges on the same side of the web asthe flange 22. The flange 22 is relatively narrow compared to the widthof the beam, being never more than one-half the width of the beam andpreferably being about one-eighth the width of the beam as is the casein the embodiment shown. The opposite sides of each of the flanges 22are accurately machined to provide pairs of longitudinally extendingtransversely spaced main guide surfaces which form an accurate straightor linear guideway or track along each beam for the carriages.

The carriage F which is generally rectangular as viewed in plan, isguided along the flange 22 of the vertical beam rail G by four wheels orrollers 23, 24, 25, 26 at the under side of the frame member 27 of thecarriage and connected to the frame member of the carriage adjacent tothe upper and lower ends thereof as viewed in H6. 2. The wheels orrollers 23, 24, 25, 26 shown are in fact the outer races ofanti-friction ball type bearings, the inner races of which are fixedlysecured to the lower end of pins or stud shafts 3h, 33, 32, 33,respectively, provided with upwardly projecting bosses all of which butone, in this instance the shaft 33, is eccentric to the axis of therespective wheel carried by the shaft.

The shafts 3b, 31, 32, 33 are provided with enlarged heads at theirlower ends against which the inner race of the bearing which forms thewheel carried thereby engages. The upper reduced ends of the shafts arethreaded and project through suitable holes in the frame 27 of thecarriage where they are provided with nuts 36 by which the shafts may befixedly secured to the frame. Suitable washers may be interposed, ifdesired, between the lower and upper ends of the inner race of eachbearing and the head of the shaft and the adjacent portion of the underside of the frame 27. A look washer is preferably employed underneaththe nut 36. A slot in the upper projecting end of the reduced portion ofeach of the shafts facilitates angular adjustment of the shafts when therespective nut 36 employed therewith loosened.

The fact that the three shafts 3t 31, and 32 are supported by eccentricportions thereof in the frame 27, provides means for adjusting thecarriage F and in turn the rulers etc. connected thereto, relative tothe guideway for the carriage formed by the opposite sides of the flange22. In assembling or setting up the device the two shafts 30, 31 at theleft hand side of the flange 22 may be adjusted to provide clearancebetween the wheels carried thereby and the adjoining side of the flange.The shaft 32 may be thereafter adjusted to obtain the desired angularrelationship between the carriage and the track and the shafts 30, 31subsequently adjusted to cause all of the wheels to firmly engage theflange 22. Alternatively, one of the shafts 3d, 31 may be omitted andthe retained shaft relocated intermediate the shafts 32, 33. The shafts32, 33 are preferably widely spaced lengthwise of the rail relative toone another so as to provide two relatively widely spaced points ofcontact with the rail and thereby reducing the tendency of the wheelscarried thereby to bind on the track, etc. The spacing should be atleast two or more times the width of the flange Z2 and in the embodimentshown is approximately ten times the flange width.

The flanges l7 and 20 on the upper sides of the beam which form thevertical beam G have portions 4%, 41 turned inwardly to overhang theside edge of the central web 15 adjacent thereto, thereby providingdiscrete supplemental guide surfaces or guideways along opposite sideedges of the beam for a plurality of outrigger rollers 42, 43, 44, 45connected to the frame 27 of the carriage F for rotation about axesparallel to the plane of the web 15. As shown, the rollers 42 to 45 arerotatably connected to outwardly projecting ends of stud shafts fixedlysecured in downwardly projecting bosses on the underside of the frame 27by nuts threaded onto their inwardly projecting ends. The rollers 42 to45 are located adjacent to the track rollers 23 to 26 respectively andprevent tilting the carriage F relative to the beam or its removaltherefrom. In other words, the rollers 42 to 45 maintain the carriage inassembled fixed relationship to the beam while leaving it free to travellengthwise thereof and be guided therealong by the guideways or tracksformed along opposite sides of the central web 22. The nuts 36, etc.,are enclosed in a housing or cover member 46 detachably connected to theframe 27 of the carriage F by suitable screws.

The carriage F is adapted to be locked or clamped in any position towhich it is moved along the beam G by lock means including a brake orfriction member 58 cnnected adjacent to the free end of a resilientlever 51 located at the lower side of the frame 27 of the carriage F anddetachably connected thereto by screws 52. The friction member 50normally travels freely in a groove 53 formed in the upper side of theflange 22 but is adapted to be pressed into tight engagement with thebottom of the groove by a screw 54 threaded in a tapped aperture in aboss '55 projecting from the upper side of the frame-27 of the carriageF. The lower end of the screw 54 abuts against the upper side of themember 51 intermediate the ends of the member and its upper end projectsoutwardly through a suitable aperture in the -cover46 where it isprovided with a knurled wheel or knob 56. Rotation of the knob 56 in theclamp direction will engage the lower surface of the member 50 with thebottom of the groove 53 to lock the carriage F to the beam rail G.Rotation in the opposite direction will allow the member 50 to be movedfree of the lower surface of the groove 53 by the resiliency of themember 51 to which it is attached to return the carriage.

The downwardly projecting flanges 18, 21 on the underside of the rail Ginclude outwardly projecting flanges 69, 61 and inwardly projectingflanges 62, 63, respectively. The latter flanges have inwardly facingV-shaped grooves 64, 65 which provide second supplemental guide surfacesforming trackways for wheels 66, 67 connected to and forming a part of acounterweight K used in connection with the vertical rail G. Oppositeends of the counterweight K are connected to opposite ends of thecarriage F by web-like flexible bands 68, 69 which are looped or reevedabout suitable rolls or pulleys 7t 71 rotatably supported in bracketsconnected to opposite ends of the beam G. In addition to providing ameans for connecting the counterweight K to the carriage F the webs 53,69 enclose the upper and lower sides of the beam, thereby providing aneat appearance and assisting in preventing the entrance of dirt and otler undesirable objects into the top side of the beam where they mightinterfere with the accurate movement of the carriage along the beam. Theprojection of the flange 22 from the web 15 is preferably less than theprojection of the side flanges 17, 20 which assists in protecting theguideway or tracks thereon from damage etc.

From the foregoing description of the manner in which the carriage F issupported and counterbalanced on the beam G it will be evident thatfriction has been reduced to a minimum and that the carriage isextremely free to be moved along the beam with minimum effort on thepart of the operator. This is accomplished in part by the use of fiatparallel guideways or tracks on opposite sides of the flange 22 and inpart by the use of a narrow flange for the guideway or track relative tothe spacing between the upper pair of rollers 23, 26 and the lower pair24, 25. It will also be noted that the outrigger rollers 42 to 45 are onthe centerline of the track and there are no forces between the carriageF and the beam. G tending to produce inaccuracies in the apparatus. Thefact that the carriage F is well counterbalanced and is freely movablealong the beam G makes it easy for the operator to place the carriage Fand in turn the rollers carried thereby in any desired position. Theconfiguration of the beam G reduces if not eliminates sag and otherdistortions even though the beam may be of considerable length.

The upper end of the beam G is provided with a bracket 75 detachablyconnected to its underside by screws 76 threaded into suitable tappedapertures in the outwardly extending flanges 69, 61 of the beam. Thebracket 75 has a tubular cylindrical projection 78 at the right-handside, as viewed in FIG. 2, and an hourglass shaped projection 79 at theleft-hand side, which projections pivotally connect the bracket 75 andin turn the vertical beam G to the frame 80 of the carriage H. Theprojections 78, 79 of bracket 75 engage within suitable apertures inupstanding flanges 81, 82, respectively, of the frame 80 of the Xcarriage H and are retained therein by cover members or hinge straps 83,84 engaging thereover and detachably connected to the upstanding flanges81, 82 by suitable screws. The construction is such that the upper endof the beam G is cradled in the horizontal carriage H such that thelower end of the beam G may be raised and lowered to pivot the beamabout the axes of the bosses 78, 79. The hourglass shape of theprojection 79 prevents am'al momentum of the bracket 75 and in turn theupper end of the beam G relative to the carriage H.

The carriage H is similar in construction to the carriage F and isconnected to the horizontal beam I in a similar manner. The frame 80 ofthe carriage H is sli htly larger and different in certain otherrespects from the frame of the carriage F. All material differences willbe referred to. As previously stated, the beam J at the upper edge ofthe board C is similar to the beam G and will not be described indetail. The corresponding parts of the beam J are, however, designatedin the drawings and will be referred to herein by the same referencecharacters employed with respect to the beam G, but having a prime markaffixed thereto. The beam I extends along the upper edge of the board Cand is connected thereto at only two points as previously mentioned bytwo brackets 85, 86 connected to the underside of the board and to theflanges 6t), 61' of the beam in a suitable manner.

The frame member 89 of the horizontal carriage H is connected to thebeam I in a manner similar to that in which the frame member 27 of thecarriage F is connected to t e beam G, and will not be described indetail. The corresponding parts, however, are designated in the drawingsby the same reference characters as those employed with respect to thecarriage F but with a prime mark afiixed thereto. Since no counterweightsimilar to the counterweight K, previously referred to, is required withthe horizontal beam J, a single web-like flexible band 9:) is employedwith the horizontal beam. The band as is reeved about suitable pulleysrotatably connected in opposite ends of the beam J and has its oppositeends detachably connected to the frame member 8% of the carriage H.

The carriage H is adapted to be secured or locked in any position alongthe horizontal beam I by friction members 91, d2, somewhat similar tothe friction member 5% previously referred to, connected to the upperside of the free end of flexible resilient members 93, 94 having flangesintegral therewith and by which they are detachably connected to theframe member 89 of the horizontal carriage H adjacent to the upper andlower sides thereof by suitable screws. The friction members 91, 92underlie the inwardly projecting flanges so, 41', respectively, at thetop side of the web 15' of the beam I and are adapted to be movedupwardly into engagement therewith by lever members 95, 96 secured tothe outwardly projecting ends of short shafts Hill, 1M rotatablysupported in downwardly projecting bosses on the underside of the framemember The inner ends of the shafts 1%, 1d} are connected to downwardlyprojecting arms of a lever m2, which lever is carried by the shafts 100,1%. The lever has an upwardly projecting arm 103 provided with a pinltid projecting therefrom in a direction parallel with the axis of theshafts 1%, TM. The projecting end of the pin 1. 34 extends into aperipheral groove in a wheellike member 1&5 fixedly connected to the endof a member 16-6 slidably supported in the boss 78 of the bracket 75',previously referred to. A tension spring 110 connected to a projectionill on the lever m2 and to an upstanding member 112 on the frame member8a; of the carriage H continuously biases the lever in acounterclockwise direction as viewed in FIG. 5; that is, in a directionto allow the friction members 91, 92 to occupy positions free of theflanges li), 41', under the resiliency of the members 93, 9d. Movementof the lever 102 by the spring 110 is limited by a collar-like spacer113 interposed on the member 1% between the wheel-like member 1% and theadjacent side of the upstanding part 81 of the frame member 80 withinwhich the boss 73 is rotatably supported.

The member ms is adapted to be moved toward the right as viewed in FIGS.2 and 5 to pivot the lever 102 and in turn, the levers 95, 96 in adirection opposite to the action of the spring Illifi; that is, in adirection to engage the friction members 91, 92 with the flanges 4f),41' by an arcuate shaped member or wedge 115 of gradually increasingwidth pivotally connected to one end of a walking beam-type lever 116and having its narrow, free end projecting between the roller 117carried by the member 1% and a roller 118 connected to the bracket '75.The lever 116 is pivotally connected to the bracket '75 and theconstruction of the wedge 115, etc., is such that oscillation of thelever 116 will cause the wedge 115, which has a gradually increasingwidth, to be projected and withdrawn from between the rollers 117, 118,thereby causing the friction members 91, 92. to engage the flanges 46?,id or to allow them to move away therefrom. The member 1% is heldagainst rotation in the boss '78 by suitable flanges on the wheel 117.

Provision is made for oscillating the lever 216 about its pivotalconnection to the bracket 75 in the form of a rod located in anoutwardly facing groove in the vertical beam G formed by the flanges 29,23. The rod 126 extends from a point adjacent to the upper end of thebeam G to a point near the lower end of the beam and is slidablyconnected to the beam G by suitable spaced brackets 12.1 positioned atdesired locations along the lefthand side of the vertical beam G, asviewed in FIGS. 1, 2, 4 and 7. The upper end of the rod 12 is connectedto the end of the lever lid opposite to the end to which the lever isconnected by a pin I122 fixed in the rod 12d and engaging within a slot123 in the lever lid. The lower end of the lever 12b is provided with agrasp 12d projecting outwardly from the left-hand side of the verticalbeam G. The grasp 126 is located at a convenient position along thevertical beam G and facilitates the convenient clamping and unclarnpingof the horizontal carriage F with respect to the beam 3. Two brackets121 located at opposite sides of the grasp 126 form stops which limitmovement of the rod iii-ll along-the beam G. One of the advantages ofthe mechanism just described for locking the horizontally movablecarriage H to the horizontal beam I is the fact that the vertcial beam Gcan be disconnected from and reconnected to the carriage H by merelyremoving and replacing the members 33, 84 which overlie the projections'78, 2 5 of the carriage frame member fill.

in the particular apparatus shown in H6. l, the lower edge of thedrafting board or table C is provided with a longitudinally extendingmetal bar-like member 139, preferably made of extruded aluminum whic lforms a guideway for rollers, not shown, connected to the bracket at thelower end of the vertical beam. G which supports the pulley 7%. Thisfacilitates movement of the vertical beam G relative to the board C.

The rulers A, B, the ruler supporting member D, and the protractor Eform an assembly, commonly referred to as a drafting machine head, whichis detachably connected to the Y carriage P and may be removed as aunit. The particular drafting machine head shown, per se, forms no partof the present invention and can be replaced by any desired differentdrafting machine head. The head shown is commercially available and isshown in US. patent to Charles Hubbard Little et al., No. 2,552,335,where it is shown connected to the free end of a band type parallelmotion arm. In order to facilitate or to assure that the rulers A, B, orwhatever other instruments are connected to the vertically movablecarriage F, will lie flat on the board C, the attachment means forconnecting the assembly E to the frame member of the carriage F ispreferably flexible in the plane of the board. In the embodiment shownthis means is in the form of a plate or blade 1E1 having two slotswithin which two screws carried by the frame 27 of the carriage F engageto detachably secure the drafting machine head E to the carriage. Thescrews project upwardly through the frame 27 and are provided with wingnuts 132, 133 to facilitate detaching the drafting machine head beingused at any particular time.

As will be readily appreciated, the scales A, B are of limited length,usually 12 to 18 inches, and in order to facilitate the making of largelayout drawings, etc., with no accumulative error due to repeated scaleextensions, etc. the present invention provides a plurality of tracksettings along both the X and Y beams in the form of graduations Mb, 141along the inner beveled edges of the rail beams G and 5, respectively.In the embodirnent shown, these graduations are at ten inch intervalsand the respective carriers are adapted to be accurately positioned withrespect thereto by indicator members 142, 143 connected to the carriagesF and H, res ectively. Each of the indicator members has a ti-shapednotch in the portion thereof which projects over the graduations withwhich it cooperates, which notch is preferably three times as wide asthe width of the graduations. This construction provides a simplemechanical device for increasd ing the reading sensitivity of theindicator and the graduations by a ratio of approximately 3 /2 to l. insetting the respective carriages the apex of the V-notch in theindicator connected thereto is brought over the beam graduation andpositioned so that the two triangles formed by the notch and thegraduation on either side of the graduation appear equal to the eye. Inthis way, a setting can be made repeatedly to less than .010 of an inch.The beam graduations in effect divide the drafting board into a gridpattern which, in the preferred embodiment shown, is a ten inch pattern.With this construction, different parts of a drawing can be worked uponwith complete confidence in the accuracy of one part relative toanother, regardless of the size of the drawing, since widely separatedreference points can be established with no accumulative error.

From the foregoing description of the preferred embodh ment of theinvention, it is believed that it will be apparent that the objectsheretofore enumerated and others have been accomplished and that therehas been provided a new and novel drafting apparatus of the characterdescribed which is economical to manufacture, is rugged in constructionand which will maintain its accuracy under all normal uses. The factthat the rail members "e quite wide and have the characteristics of anl-bearn assures against their distorting in use and the fact that theguide surfaces for the respective carriages are relatively closetogether with respect to the distance between the guide or track wheelsat opposite ends of the carriages assures their free and accuratemovement along their respective tracks.

As previously stated, the rail beams have a cross sectionalconfiguration which provides extreme rigidity and lack of deflection inall directions while being relatively light in weight. The side flangesprojecting in opposite directions from the side edges of the web of thebeam provide stability against deflection of the rail beams in the planeof the drawing board and are such that the vertical beam can span arelatively wide board without intermediate rollers or other supportswhich would tend to mar a drawing being made.

As also has been previously mentioned, the rail beams are preferablymade of extruded aluminum alloy, and in order to reduce the possibilityof distortions occurring in the beams subsequent to their manufacture,machining operations thereon are maintained at a minimum. To this end,the only parts of the rail beams shown which are machined are thestraight tracks or guideways along opposite sides of the narrow flange22. Since this flange is in the form of a relatively low centralprojection on the web of the beam, its accuracy is maintained eventhough the narrow sides thereof are machined. The outwardly projectingflanges on the lower edges of the beams, in addition to addingstability, provide a convenient connection for clamping the beams to thework table of the machine during the machining operation of thelongitudinal guideways on the flange 22 in a manner which will notstress the beams in a way which might cause inaccuracies.

Although the preferred embodiment of the invention has been described inconsiderable detail, the invention is not limited to the particularconstruction shown and it is the intention to hereby cover alladaptations, modifications and uses thereof which come within thepractice of those skilled in the art to which the invention relates andwithin the scope of the appended claims.

Having thus described my invention, I claim:

1. In a drafting machine of the character referred to: a relativelywide, flat rail member having a first longitudinally extending guidesurface at one side of its longitudinal center line and a secondlongitudinally extending guide surface at the other side of itslongitudinal center line; said guide surfaces being on the same side ofsaid rail member, angularly disposed to the plane of said rail member,opposed to one another and spaced from the longi tudinal center line ofsaid rail member less than the distance that they are spaced from theside edges of said rail member; a carriage adapted to have a draftinginstrument operatively connected thereto; means connecting said carriageto said rail member for movement therealong; said means comprising apair of rollers in engagement with said first guide surface; meansconnecting one of said rollers of said pair to said carriage foradjustment relative to the other roller of said pair transversely of thelength of said rail member; means releasably securing said one roller ofsaid pair of rollers in adjusted position; a third roller connected tosaid carriage and in engagement with said second guide surface; andmeans for effecting relative adjustment between both of said rollers ofsaid pair of rollers in engagement with said first guide surface andsaid third roller in engagement with said second guide surfacetransversely of the length of said rail member.

In a drafting machine of the character referred to, a rail member havinga relatively wide Web portion provided with a pair of longitudinallyextending transversely spaced opposed guide surfaces at opposite sidesof its longitudinal center line, said guide surfaces being disposed atan angle to the plane of said web and spaced from the longitudinalcenter line thereof less than the distance that they are spaced from theside edges of said rail member, a carriage adapted to have a draftinginstrument operatively connected thereto, means connecting said carriageto said rail member for movement therealong, said means comprising apair of rollers connected to said carrier and in en agement with one ofsaid guide surfaces at one side of said center line of said rail memberand a third roller connected to said carriage and in engagement with theother of said guide surfaces at the other side of said center line ofsaid rail member, means for adjusting one of said rollers of said pairof rollers relative to the other roller of said pair in a directiontransversely of the length of said rail member, means for releasablysecuring said one roller of said pair in adjusted position, and meansfor moving said third roller relative to said carriage in a directiontransversely of the length of said rail member.

3. In a drafting machine of the character referred to, a rail membercomprising a relatively wide web portion provided with a pair oflongitudinally extending transversely spaced opposed guide surfaces atopposite sides of its longitudinal centerline disposed at an angle tothe plane of said web portion and supplemental guide surfaces adjacentto opposite side edges of said rail member, said guide surfaces of saidpair being spaced from the longitudinal center line of said web portionless than the distance that they are spaced from the side edges of saidrail member, a carriage adapted to have a drafting instrumentoperatively connected thereto, a pair of rollers in engagement with oneof said pair of guide surfaces and connected to said carriage foradjustment relative to one another transversely of said rail member,means for releasably securing said rollers in adjusted position, a thirdroller in engagement with the other of said pair of guide surfaces andconnected to said carriage for movement transversely of said railmember, and means on said carriage in engagement with said supplementalguide surfaces adjacent to the side edges of said rail member.

4. In a drafting machine of the character referred to, a rail memberhaving a relatively wide web portion provided with a pair oflongitudinally extending transversely spaced guide surfaces at oppositesides of the longitudinal centerline of the web portion and extendingnormal to the .plane of said web portion and supplemental longitudinallyextending guide surfaces adjacent to the side edges of said memberdisposed at an angle to said first guide surfaces, said guide surfacesof said pair being spaced from the longitudinal center line of said webpontion less than the distance that they are spaced from the side edgesof said rail member, a carriage adapted to have a drafting instrumentoperatively connected thereto, a pair of rollers in engagement with oneof said pair of guide surfaces and connected to said carriage forrelative adjustment with respect to one another transversely of saidrail member, means for releasably securing said rollers in adjustedposition, a third roller in engagement with the other of said pair ofguide surfaces and connected to said carriage for movement transverselyof said rail member, and means on said carriage engaging saidsupplemental, guide surfaces.

5. in a drafting machine of the character referred to, a rail memberhaving a relatively Wide web portion provided on one side with a pair oflongitudinally extending transversely spaced opposed main guide surfacesat opposite sides of the longitudinal centerline of the web portion anddisposed at an angle to the plane of said Web portion and supplementallongitudinally extending guide surfaces at opposite sides of both edgeportions of said rail member disposed at an angle other than 90 to theplane of said web portion, said main guide surfaces being spaced fromthe longitudinal center line of said web portion of said rm'l memberless than the distance that they are spaced from the side edges of saidrail member, a carriage adapted to have a drafting instrumentoperatively connected thereto, a pair of rollers in engagement with onemain guide surface of said pair of main guide surfaces and connected tosaid carriage for relative adjustment With respect to one anothertransversely of said rail member, means for releasably securing saidrollers in adjusted position, a third roller in engagement with theother of said main guide surfaces of said pair of main guide surfacesand connected to said carriage for movement transversely of said railmember, means on said carriage engaging said supplemental uide surfaceson said one side of said rail member, counterweight means movablysupported on said supplemental guide surfaces on the other side of saidrail member, and means extending around the top end of said rail memberconnecting said carriage and said counterweight means.

6. In a drafting machine of the character referred to, a firstrespectively Wide fiat rail member having longitudinally extendingtransversely spaced guide surfaces at opposite sides of its longitudinalcenterline and angularly disposed to the plane thereof, said guidesurfaces of said first rail member being spaced from the longitudinalcenter line thereof less than the distance that they are spaced from theside edges of said first rail member, a first carriage, means connectingsaid first carriage to said first rail member comprising a first pair ofrollers in engagement with one of said guide surfaces of said pair ofguide surfaces on said first rail member and connected to said firstcarriage for relative adjustment With respect to one anothertransversely of said first rail member and a third roller in engagementwith the other of said guide surfaces of said pair of guide surfaces onsaid first rail member and connected to said first carriage for movementtransversely of said first rail member, means for releasably securingsaid first pair of rollers in adjusted position, a second relativelywide flat rail member having longitudinally extending transverselyspaced guide surfaces at opposite sides of its longitudinal centerlineand angularly disposed to the plane of said second rail member, saidguide surfaces of said second rail member being spaced from thelongitudinal center line thereof less than the distance that they arespaced from the side edges of said second rail member, means forpivotally connecting said second rail member to said first carriage formovement about an axis extending lengthwise of said first rail member, asecond carriage adapted to have a drafting instrument operativelyconnected thereto, means connecting said second carriage to said secondrail member comprising a second pair of rollers in engagement with oneof said guide surfaces of said pair of guide surfaces on said secondrail member and connected to said second carriage for relativeadjustment with respect to one another transversely of said second railmember means for releasably securing said second pair of rollers inadjusted position, and a sixth roller in engagement with the other ofsaid guide surfaces of said pair of guide surfaces on said second railmember and connected to said second carriage for movement transverselyof said second rail member.

7. In a drafting machine of the character referred to, a first railmember having a relatively wide web portion provided with a pair oflongitudinally extending transversely spaced main guide surfaces atopposite sides of the longitudinal centerline of the Web portion of saidfirst rail member and disposed at an angle to the plane of said webportion of said first rail member and supplemental longitudinallyextending guide surfaces adjacent to the side edges of said first railmember disposed at an angle other than to the plane of said Web portionof said first rail member, said main guide surfaces of said first railmember being spaced from the longitudinal center line thereof less thanthe distance that they are spaced from the side edge-s of said firstrail member, a first carriage, a first pair of rollers in engagementwith one of said main guide surfaces of said pair of main guide surfaceson said first rail member and connected to said first carriage forrelative adjustment with respect to one another transversely of saidfirst rail member, means for releasably securing said first pair ofrollers in adjusted position, a third roller in engagement with theother of said main guide surface of said pair of main guide surfaces onsaid first rail member and connected to said first carriage foradjustment transversely of said first rail member, means for releasablysecuring said third roller in adjusted position, means on said firstcarriage engaging said supplemental guide surfaces on said first railmember, a second rail member having a relatively wide web portionprovided with a pair of longitudinally extending transversely spacedmain guide surfaces at opposite sides of the longitudinal centerline ofthe web portion of said second rail member and disposed at an angle tothe plane of said Web portion of said second rail member andsupplemental longitudinally extending guide surfaces adjacent to theside edges of said second rail member disposed at an angle other than 90to the plane of said web portion of said second rail member, said mainguide surfaces of said second rail member being spaced from thelongitudinal center line thereof less than the distance that they arespaced from the side edges of said second rail member, a second carriageadapted to have a drafting instrument operatively connected thereto, asecond pair of rollers in engagement with one of said pair of main guidesurfaces on said second carriage and connected to said second carriagefor relative adjustment with respect to one another transversely of saidsecond rail member, means for releasably securing said second pair ofrollers in adjusted position, a sixth roller in engagement with theother of said pair of main guide surfaces on said second rail member andconnected to said second carriage for adjustment transversely of saidsecond rail member, means for releasably securing said sixth roller inadjusted position, and means on said second carriage engaging saidsupplemental guide surfaces on said second rail member.

8. In a drafting machine of the character referred to a first railmember having a cross sectional shape resembling that of an l-beam, saidfirst rail member having on one side a pair of longitudinally extendingtransversely spaced guide surfaces at opposite sides of the longitudinalcenterline of its web and disposed at right angles to the plane of saidweb portion and supplemental guide surfaces along both edge portionsthereof and disposed at an angle to said pair of guide surfaces, saidguide surfaces of said pair being spaced from the longitudinal centerline of said web portion less than the distance that they are spacedfrom the side edges of said first rail member, a first carriage, a firstpair of rollers in engagement with one of said guide surfaces of saidpair of guide surfaces on said first rail member and connected to saidfirst said carriage for relative adjustment with respect to one anothertransversely of the length of said first rail member, means forreleasably securing said first pair ofrollers in adjusted position, athird roller in engagement with the other of said guide surfaces of saidpair of guide surfaces on said first rail member and connected to saidfirst carriage for adjustment transversely of said first rail member,means for releasably securing said third roller in adjusted position,means on said first carriage engaging said supplemental guide surfaceson said first rail member, a second rail member having a cross sectionalshape resembling that of an I-beam, said second rail member having onone side a pair of longitudinally extending transversely spaced guidesurfaces at opposite sides of the longitudinal centerliue of its web anddisposed at right angles to the plane of said web portion andsupplemental longitudinally extending-guide surfaces on opposite sidesof both edge portions of said second rail member angularly disposed tothe plane of said pair of guide surfaces on said second rail member,said guide surfaces of said pair being spaced from the longitudinalcenter line of said web portion less than the distance that they arespaced from the side edges of said second rail member, means forpivotally connecting one end of said second rail member to said firstcarriage for movement about an axis lengthwise of said first railmember, a second carriage adapted to have a drafting instrumentoperatively connected thereto, a second pair of rollers in engagementwith one of said guide surfaces of said pair of guide surfaces onsaidsecond member and connected to said carriage for relative adjustmentwith respect to one another transversely of said rail member, means forreleasably securing said second pair of rollers inadjusted position, asixth roller in engagement with the other guide surface of said pair ofguide surfaces on said second rail member and connected to said secondcarriage for adjustment transversely of said second rail member, meansfor releasably securing said sixth roller in adjusted position, means onsaid second carriage engaging said supplemental guide surfaces on theside of said second rail member upon which said pair of guide surfacesis located, counterweight means movably supported on said guide surfaceson the other side of said second rail member, means extending aroundopposite ends of said second rail member connecting said second carriageand said counterweight means.

'9, In a drafting machine of the character referred to a relativelywide, flat rail member having longitudinally extending opposed guidesurfaces spaced with respect to one another transversely of the railmember a distance less than one-fourth the Width of the rail member,said guide surfaces being angularly disposed with respect to the planetherealong, said means comprising a pair of rollers connected to saidcarriage and in engagement with one of said guide surfaces, means foradjusting one of said rollers of said pair of rollers relative .to theother roller of said pair in a direction transversely of the length ofsaid rail member, means for releasably securing said roller in adjustedposition, a third roller connected to said carriage and in engagementwith the other of said guide surfaces, and for moving said third rollerrelative to said carriage in a direction transversely of the length ofsaid rail member.

10. In a drafting machine of the character referred to a relativelywide, flat rail member having longitudinally extending opposed guidesurfaces spaced With respect to one another transversely of the railmember a distance less than one-fourth the width of the rail member,said guide surfaces being angularly disposed with respect to the planeof said rail member, said rail member also having supplemental guidesurfaces adjacent to opposite side edges thereof, a carriage adapted tohave a drafting instrurnent operatively connected thereto, meansconnecting said carriage to said rail member for movement therealong,said means comprising a pair of rollers connected to said carriage andin engagement with one of said guide surfaces, means for adjusting oneof said rollers of said pair of rollers relative to the other roller ofsaid pair in a direction transversely of the length of said rail member,means for releasably securing said roller in adjusted position, a thirdroller connected to said carriage and in engagement with the other ofsaid guide surfaces, means for moving said third roller relative to saidcarriage in a direction transversely of the length of said rail member,and means on said carriage engaging said supplemental guide surfaces.

References Cited in the file of this patent UNITED STATES PATENTS1,149,120 Fortune Aug. 3, 1915 1,623,406 Hand Apr. 5, 1927 2,879,715Bohlin Mar. 31, 1959 FORETGN PATENTS 238,718 Germany Oct. 3, 1911

1. IN A DRAFTING MACHINE OF THE CHARACTER REFERRED TO: A RELATIVELYWIDE, FLAT RAIL MEMBER HAVING A FIRST LONGITUDINALLY EXTENDING GUIDESURFACE AT ONE SIDE OF ITS LONGITUDINAL CENTER LINE AND A SECONDLONGITUDINALLY EXTENDING GUIDE SURFACE AT THE OTHER SIDE OF ITSLONGITUDINAL CENTER LINE; SAID GUIDE SURFACES BEING ON THE SAME SIDE OFSAID RAIL MEMBER, ANGULARLY DISPOSED TO THE PLANE OF SAID RAIL MEMBER,OPPOSED TO ONE ANOTHER AND SPACED FROM THE LONGITUDINAL CENTER LINE OFSAID RAIL MEMBER LESS THAN THE DISTANCE THAT THEY ARE SPACED FROM THESIDE EDGES OF SAID RAIL MEMBER; A CARRIAGE ADAPTED TO HAVE A DRAFTINGINSTRUMENT OPERATIVELY CONNECTED THERETO; MEANS CONNECTING SAID CARRIAGETO SAID RAIL MEMBER FOR MOVEMENT THEREALONG; SAID MEANS COMPRISING APAIR OF ROLLERS IN ENGAGEMENT WITH SAID FIRST GUIDE SURFACE; MEANSCONNECTING ONE OF SAID